Spark plug and method of making the same



Oct. 7 1924.

1,511,199 A. GHAMPION ET AL SPARK PLUG AND METHOD OF MAKING THE SAMEFiled April 14 1921 Patented Oct. 7, 1924.

UNITED STATES PATENT" OFFICE.

AIIBERT CHAMPION, OF FLINT, AND LLOYD BLACKMORE, OF HIGHLAND PARK,MICHIGAN, ASSIGNORS TO A C SPARK PLUG COMPANY OF DETROIT, MICHIGAN,

A CORPORATION OF MICHIGAN.

SPARK PLUG AND METHOD OF MAKING THE SAME.

Application filed. April 14, 1921. Serial No. 461,237.

To all whom it may concem:

Be it known that we, ALBERT CHAMPION, a citizen of the United States,and resident of Flint, Genesee County, Michigan, and LLoYo BLAOKMORE, asubject of the King of Great Britain, and resident of Highland Park,Wayne County, State of Michigan, have invented certain new and usefulImprovements in Spark Plugs and Methods of Making the Same, of which thefollowing is a full, clear, concise, and exact description, such as willenable others skilled in the art to which the invention relates to makeand use the same, reference being made therein to the accompanyingdrawings, which form a part of this specification.

Our invention relates to spark plugs of the type or class commonlyreferred to as single piece plugs, because of the fact that after theinsulator of the plug has been assembled with and secured in placewithin the shell or casing of the plug the parts cannot be disassembledwithout destroying the plug; thus providing a plug the insulator ofwhich cannot be removed by the user with a resulting impairment of thegas tight qualities of the lug, as it is diflicult if indeed not impossile after having removed the insulator from the casing to replace it insuch a way as to prevent leakage of gas through the joint between theparts.

More specificall stated, our invention relates to and the ohject thereofis to provide an improved shell or casing for spark plugs of the type orclass above referred to; said improved casing being one which may bemore readily and cheaply manufactured than has heretofore commonly beenthe case, with a resulting reduction in cost of the finished shell andof the plug of which it forms a part. 4

\ A further object of our invention is to provide an improved spark plugshell or casing made from sheet metal stock by subjecting the same tosuitable forming,

drawing-shaping and similar operations, as distinguished from formingthe same from solid bar or rod stock, as has heretofore commonly beenthe cas I A further object of our invention is-to provide an improvedform of shell or casing for single piece spark plugs of the type abovereferred to.

A further object" of our invention is to provide an improved method orprocess of making shells or casings for single piece spark plugs; and astill further object of our invention is to provide an improved singlepiece spark plug and an improved method or process'of making the same.

With the above and other objects of invention in view, our inventionconsists in the improved single piece spark plug and method of makingthe same, and in the improved spark plug casing or shell and method ofmaking the same illustrated in the accompanying drawing and hereinafterdescribed and particularly claimed; and in such variations andmodifications thereof, within the scope of the concluding claims, aswill be obvious to those skilled in the art to which my inventionrelates.

In the drawing accompanying and forming a part of this application andwherein the referred embodiment of our invention is il ustrated:

Figure 1' is a view partly in section and partly in side elevationshowing a single piece spark plug the shell or casin of which is made inaccordance with on invention.

Figures 2, 3 and 4 are views showing three distinctive conditionsassumed by the piece of metal from which the upper or outer section ofthe plug casing is formed, as the same is subjected to the variousmanufacturin steps or operations whereby it is produced.

Figures 5, 6 and 7 are views similar to Figures 4 to 6, but showing thelower or inner section of the casing at three distinct sta es of itsmanufacture.

eferring shell or casing of ourimproved single piece spark plug is madeup of an outer section 8 substantially tubular in form,and having aninwardly extending ledge 9 at its upper end overlying the upper shoulder10 of the porcelain or equivalent insulator 11 of the plug, and an innersubstantially tubular section 12'having a shoulder 13 adjacent its upperend for supporting the lower shoulder 14 of the insulator; the meetingends of the two sections bein joined along a joint at 15, preferabl by eectrically welding the meeting ends 0 the sections together. The

to the drawing, the externalinner casing section is threaded upon itsperiphery so that the plug may be screwed into athreaded spark plugopening in an engine cylinder, and the exterior surface of the uppercasing section is shown as octagonal in form so that the plug may bescrewed into place by a suitable wrench.

In making the plug illustrated in Figure 1 the tubular casing sectionsare placed over the insulating member as shown, suitable gaskets beingordinarily placed between the ledge 9 and shoulder 10, and between theledge 13 and the shoulder 14; and the assembled plug is inserted betweenpressure applying jaws or clamps of an electrical weld ing devicedesignated conventionally by the letters -A and ,B and which areconnected with a source of electricity, so that the parts may be pressedtogether while a welding current is caused to flow through thecontacting surface at the abutting ends of the casing sections thuselectrically welding the sections together along the joint 15. At thesame time the pressure applied to the casing sections to accomplish thewelding I compresses the gaskets referred to to a degree proper-tosecure gas tight joints -be- -tween the insulator and the casing, themovement of the sections toward one another resulting in a slightupsetting at the abutting edges as shown; so that the act ofelectrically welding the contacting ends of the easingtogether securesalso the necessary'gas tight joints between the casing and the insulatorlocated therein.

The substantially tubular casing sections 8 and 12 may be made frompieces of tubing cut to proper length and shaped to provide the flanges9 and 13 by the use of suitable dies, or made otherwise in accordancewith approved manufacturing processes. In Figures 2 to 7, however, wehave shown these members as formed from discs of sheet or thin platemetal stock by the use of suitable shaping, drawing, cutting and otherappropriate operations; thus providingfor the making of the parts of theshell or casing and, as follows, the complete casing of the plug fromsheet metal stock; which enables the shell to be made at slight cost,and with a minimum waste of material.

Thus Figure 2 shows a cup-shaped mem: ber 16 made from a fiat circulardisc of metal by forcing it the proper number of times through suitabledrawing dies by the use of suitable plungers; and Figure 3 shows the cupafter it has been forced through dies of proper form to impart anoctagonal form to the side wall 17 and to the peripheral surfacethereof, and after the end wall 18 of the cup has been partially shapedto provide the inwardly extending holding ledge 9 hcreinbefore referredto. Thereafter, and after such further shaping operations as may benecessary to impart the proper form to the section being operated upon,the central portion of the end wall 18 is removed as by a suitable punchand die; thus providing an opening 19 through which the upper end of theinsulating member 11 extends, and leaving the inturned ledge 9 in theform necessary to hold the insulator in place within the shell when thesections thereof are assembled and welded together as hereinbeforeexplained.

By subjecting a sheet metal disc of proper diameter to suitable drawing,forming, shaping, punching and equivalent steps the same may be made toassume the cup form 20 shown in Figure 5; then the form shown in Figure6 with the offset supporting flange or shoulder 21 adjacent the upperend thereof; and finally, after the head 22of the cup has been punchedout, to assume the form shown in Figure 7 which is that of the finishedlower or inner casing section; the threads shown in said figure havingbeen cut by a separate operation and the shoulder 21 having beensmoothed up or otherwise finished, when such a course is deemednecessary, to provide the supporting shoulder 13 adjacent the upper endof the said lower or inner casing section.

While as herein explained it is necessary in the manufacture of sparkplugs in accord ance with our invention that the pressure applied to thetubular casing sections be maintained while their free edges are beingwelded together, in order that the tight joints thus produced betweenthe insulator and the portions of the sections which hold Y the same inplace within the shell shall persist, and be maintained in the completedplug so that leakage of gas past the joints will be prevented, it is notessential that the welding shall be of the character commonly implied bythe term and in which there shall be no metal at the joint other thanthe metal of the sections themselves; as we intend in some cases toaccomplish the Welding by running in or ama'lgamating a. third metal atthe joint in accordance with methods of weldin wherein parts are joinedwholly or in part y a Wire, strip, ori otherwise shaped piece of metalfused adjacent the joint to be formed, and permitted to run in betweenthe parts to be joined together.

Having thus described and explained our invention, we claim and desireto secure by Letters Patent:

1. The method of making a spark plug which consists in assembling aninsulating member within two tubular casing sections having free edgesadapted to engage one another, and each of which sections is providedwith holding means adapted to on ago said insulating member and hold itin ace within the casing formed by said to ular members; applyingpressure to said tubular members to force them toward one another;

and welding the free edges of said casing sections together while theforce applied to said members is maintained. I

2. The method of making a spark plug which consists in assembling aninsulating member within two tubular casing sections having their freemeeting edges in contact, and which casing sections are so formed as tograsp said insulator and hold the same permanently within the casingformed by said casin sections; and simultaneously forcing sai sectionstoward one another and weldin their abutting edges together.

3. T e method of making a spark plug which consists in assembling aninsulating member within two tubular casing sections havin their freemeeting edges in contact,

and w ich casing sections are so formed as to grasp said insulator andhold the same permanently within the casing formed by said casingsections; and simultaneously forcing said sections toward one anotherand cansing a welding current of electricity to flow through the oint attheir contacting ed s.

4. The method of making a spark p ug shell or casing which consists inassembling two tubular casing members or sections so formed as toreceive and support an insulator in line with one another, with theirends in contact; and welding the abutting ends of said casing members tother.

5. The method of making a spark shell or casing which consists informing two cup-shaped members from sheet metal, and properly shapingsaid members and removmg the end walls thereof to thereby provide twotubular casing'members or sections; as-

. sembling said casing members in line with plug one another and withtheirends in contact; and welding the abutting ends of said casingsections together.

6. In a sparkplug, two tubular casing members or sections havingabutting ends welded together; and an insulating member located withinthe casing thus formed.

7. In a spark plug, two tubular casing members or sections havingabuttin ends welded together; supporting means ocated within one of saidmembers; holding means carried by the other of said members; and aninsulating member located within the easin thus formed and held in placebetween said supporting and holding means.

8. A spark lug comprising a shell or casing made up of two tubularcasing members arranged in line, and the abutting ends oi which arewelded together; and an insulat ing member permanently held in placewithin said shell.

9. A spark plug comprising a shell or casing made up of two tubularcasing members arranged in line with one another and th abutting ends ofwhich are welded together; a supporting shoulder located within saidcasing and adjacent the joint between said casing members and in one ofsaid members; an inturned holding flange located at the .free end of theother of said casing members; and an insulating member located withinsaid casing and permanently held in place between said supportingshoulder and said-inturned flange.

In testimony whereof we aiiix our signatures.

ALBERT CHAMPION. LLOYD BLACKMORE.

